2011Z4Newbie
Member
Hey everyone,
I’m driving a 2016 BMW Z4 20i (N20 engine) and I’ve been dealing with some lumpy/hesitant acceleration, especially noticeable at low RPMs. No engine lights at first, but the performance wasn’t smooth—felt like a slight misfire or lag.
I ran a scan using Car Scanner, and here are the key fault codes I pulled:
• 3429 – Cylinder 4 Exhaust Valve Control Circuit/Open
• 31E9 – Electric Fan Self-Diagnosis Fault (Inactive/Archived)
I’ve read that 3429 often relates to VANOS or oil pressure issues. So here’s what I’ve done so far:
• Removed and cleaned the Oil Pressure Control Valve (OPCV) thoroughly with brake cleaner.
• Found a bit of oil/sludge buildup but nothing crazy.
• Let it dry fully, cleaned the bore as best I could (there was a pinch-fitted mesh/washer deep in the housing, which I left in place and cleaned carefully).
• Reinstalled everything, but haven’t cleared codes or road tested yet.
Notes:
• I haven’t removed or cleaned the VANOS solenoids yet, as I originally mistook the OPCV for one of them. I am unsure if the solenoids can actually be taken out fully without an engine disassembly.
• Battery voltage was a bit low during the scan (~11.8V), so I’m also watching that.
Has anyone dealt with this exact 3429 code before? Could a faulty solanoid alone cause it, or am I looking at replacing the VANOS solenoid next, this looks like it needs to be done at a dealership as there is no access to take them out, only the front actuators (see images)
Any advice or shared experience would be hugely appreciated before I start buying parts or booking it in.
Thanks in advance!
I’m driving a 2016 BMW Z4 20i (N20 engine) and I’ve been dealing with some lumpy/hesitant acceleration, especially noticeable at low RPMs. No engine lights at first, but the performance wasn’t smooth—felt like a slight misfire or lag.
I ran a scan using Car Scanner, and here are the key fault codes I pulled:
• 3429 – Cylinder 4 Exhaust Valve Control Circuit/Open
• 31E9 – Electric Fan Self-Diagnosis Fault (Inactive/Archived)
I’ve read that 3429 often relates to VANOS or oil pressure issues. So here’s what I’ve done so far:
• Removed and cleaned the Oil Pressure Control Valve (OPCV) thoroughly with brake cleaner.
• Found a bit of oil/sludge buildup but nothing crazy.
• Let it dry fully, cleaned the bore as best I could (there was a pinch-fitted mesh/washer deep in the housing, which I left in place and cleaned carefully).
• Reinstalled everything, but haven’t cleared codes or road tested yet.
Notes:
• I haven’t removed or cleaned the VANOS solenoids yet, as I originally mistook the OPCV for one of them. I am unsure if the solenoids can actually be taken out fully without an engine disassembly.
• Battery voltage was a bit low during the scan (~11.8V), so I’m also watching that.
Has anyone dealt with this exact 3429 code before? Could a faulty solanoid alone cause it, or am I looking at replacing the VANOS solenoid next, this looks like it needs to be done at a dealership as there is no access to take them out, only the front actuators (see images)
Any advice or shared experience would be hugely appreciated before I start buying parts or booking it in.
Thanks in advance!
